The present invention relates to means and method for increasing the power rating of an offshore high voltage power cable which includes passage of the cable from the sea to a platform installation through a bending strain reliever (BSR). A technical problem is related to the fact that the power rating of the cable is lower through the BSR (some 30%) than through the water.
EP 777034 A1 (NO 965068) relates to a `stiffening element for a flexible pipeline in a marine environment`. When the pipeline contains hot fluid the polyurethane BSR is damaged over time and this problem is overcome by passing cooling sea water through ducts made in the BSR. This construction could probably also be used for high voltage power cables, but requires a special BSR.
The object of the present invention is to increase the power rating of a high voltage power cable passing through the BSR without having to use a special BSR.
The main features of the invention are defined in the, accompanying claims. For installation purposes,--the inner diameter of the BSR will have to be slightly greater than the outer diameter of the cable, and the basic idea is to circulate cooling fluid (water) in the interface space between the cable and the BSR and provide suitable inlet and outlet for the fluid.
The solution which eliminates the power loss through the BSR has been proven to be workable by calculations based on a 5-10 mm diameter difference between the BSR and the cable with circulation of a cooling fluid at a rate of 5-10 l/min.